воскресенье, 22 декабря 2019 г.

Afanasievo people may well have been proto-Tocharian speakers (Ning et al. 2019)

Update 17/08/2019: A surprising twist to the Shirenzigou nomads story ... During the Early Bronze Age, around 2,900 BCE, a population associated with the Yamnaya archeological culture migrated from the Pontic-Caspian steppe in Eastern Europe deep into Asia, as far as the Minusinsk Basin in South Siberia. This rapid, long-range expansion was likely to have been the first significant migration

* This article was originally published here

They mixed up Huns with Tocharians

I don't yet have the genomes from the recent Ning et al. paper on the Iron Age nomads from the Shirenzigou site in the eastern Tian Shan. But I do have most of the previously published data featured in the paper, including the Damgaard et al. 2018 Hun and Saka samples from the western Tian Shan. After reading the Ning et al. paper between the lines and running a few analyses of my own, it's

* This article was originally published here

A surprising twist to the Shirenzigou nomads story

Remember those potentially Afanasievo-derived and Tocharian-related Shirenzigou nomads from the Ning et al. paper? Well, in my opinion, they're probably neither. The genotypes and other data for these Iron Age individuals from the eastern Tian Shan are available here. Below are a few successful and not so successful qpAdm mixture models for them. Note that I tried to use a wide range of

* This article was originally published here

NASA’s SDO Sees New Kind of Magnetic Explosion on Sun

Forced magnetic reconnection, caused by a prominence from the Sun, was seen for the first time in images from NASA’s Solar Dynamics Observatory, or SDO. This image shows the Sun on May 3, 2012, with the inset showing a close-up of the reconnection event imaged by SDO’s Atmospheric Imaging Assembly instrument, where the signature X-shape is visible. Credit: NASA/SDO/Abhishek Srivastava/IIT(BHU).​

NASA’s Solar Dynamics Observatory has observed a magnetic explosion the likes of which have never been seen before. In the scorching upper reaches of the Sun’s atmosphere, a prominence — a large loop of material launched by an eruption on the solar surface — started falling back to the surface of the Sun. But before it could make it, the prominence ran into a snarl of magnetic field lines, sparking a magnetic explosion.

Scientists have previously seen the explosive snap and realignment of tangled magnetic field lines on the Sun — a process known as magnetic reconnection — but never one that had been triggered by a nearby eruption. The observation, which confirms a decade-old theory, may help scientists understand a key mystery about the Sun’s atmosphere, better predict space weather, and may also lead to breakthroughs in the controlled fusion and lab plasma experiments.

“This was the first observation of an external driver of magnetic reconnection,” said Abhishek Srivastava, solar scientist at Indian Institute of Technology (BHU), in Varanasi, India. “This could be very useful for understanding other systems.  For example, Earth’s and planetary magnetospheres, other magnetized plasma sources, including experiments at laboratory scales where plasma is highly diffusive and very hard to control.”

Previously a type of magnetic reconnection known as spontaneous reconnection has been seen, both on the Sun and around Earth. But this new explosion-driven type — called forced reconnection — had never been seen directly, thought it was first theorized 15 years ago. The new observations have just been published in the Astrophysical Journal.

The previously-observed spontaneous reconnection requires a region with just the right conditions — such as having a thin sheet of ionized gas, or plasma, that only weakly conducts electric current — in order to occur. The new type, forced reconnection, can happen in a wider range of places, such as in plasma that has even lower resistance to conducting an electric current. However, it can only occur if there is some type of eruption to trigger it. The eruption squeezes the plasma and magnetic fields, causing them to reconnect.

While the Sun’s jumble of magnetic field lines are invisible, they nonetheless affect the material around them — a soup of ultra-hot charged particles known as plasma. The scientists were able to study this plasma using observations from NASA’s Solar Dynamics Observatory, or SDO, looking specifically at a wavelength of light showing particles heated 1-2 million kelvins (1.8-3.6 million F).

The observations allowed them to directly see the forced reconnection event for the first time in the solar corona — the Sun’s uppermost atmospheric layer. In a series of images taken over an hour, a prominence in the corona could be seen falling back into the photosphere. En route, the prominence ran into a snarl of magnetic field lines, causing them to reconnect in a distinct X shape.

Forced magnetic reconnection, caused by a prominence from the Sun, was seen for the first time in images from NASA’s SDO. Credits: NASA's Goddard Space Flight Center.Download this video in HD formats from NASA Goddard's Scientific Visualization Studio

Spontaneous reconnection offers one explanation for how hot the solar atmosphere is — mysteriously, the corona is millions of degrees hotter than lower atmospheric layers, a conundrum that has led solar scientists for decades to search for what mechanism is driving that heat. The scientists looked at multiple ultraviolet wavelengths to calculate the temperature of the plasma during and following the reconnection event. The data showed that the prominence, which was fairly cool relative to the blistering corona, gained heat after the event. This suggests forced reconnection might be one way the corona is heated locally. Spontaneous reconnection also can heat plasma, but forced reconnection seems to be a much more effective heater — raising the temperature of the plasma quicker, higher, and in a more controlled manner.

While a prominence was the driver behind this reconnection event, other solar eruptions like flares and coronal mass ejections, could also cause forced reconnection. Since these eruptions drive space weather — the bursts of solar radiation that can damage satellites around Earth — understanding forced reconnection can help modelers better predict when disruptive high-energy charged particles might come speeding at Earth.

Understanding how magnetic reconnection can be forced in a controlled way may also help plasma physicists reproduce reconnection in the lab. This is ultimately useful in the field of laboratory plasma to control and stabilize them.
The scientists are continuing to look for more forced reconnection events. With more observations they can begin to understand the mechanics behind the reconnection and often it might happen.

“Our thought is that forced reconnection is everywhere,” Srivastava said. “But we have to continue to observe it, to quantify it, if we want prove that.”




Related Links 

By Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Editor: Rob Garner




* This article was originally published here

Tomnaverie Prehistoric Recumbent Stone Circle, Tarland, Aberdeenshire, 20.12.19.

Tomnaverie Prehistoric Recumbent Stone Circle, Tarland, Aberdeenshire, 20.12.19.



* This article was originally published here

Updated Eurogenes K13 now at GEDmatch


The new K13 population averages and genetic (Fst) distances between the inferred ancestral clusters are available here and here, respectively. To find this test at GEDmatch do this:

GEDmatch > Ad-Mix Utilities > Eurogenes > K13

Below is a 2D PCA based on the average K13 results of the European and Asian reference populations, courtesy of project member PL16.


I now have four tests at GEDmatch with Oracles: the Jtest, EUtest, K15 and K13. It's useful to keep in mind that these tests will differ in their interpretation of the data, and perhaps accuracy, depending on the ancestry of the user. For instance, the new K13 should be more useful for Central and South Asians than any of the others, because it features new reference samples relevant to them.



* This article was originally published here

2019 December 22 Solstice Illuminated: A Year of Sky Video...



2019 December 22

Solstice Illuminated: A Year of Sky
Video Credit & Copyright: Ken Murphy (MurphLab); Music: Ariel (Moby)

Explanation: Can you find which day is the winter solstice? Each panel shows one day. With 360 movie panels, the sky over (almost) an entire year is shown in time lapse format as recorded by a video camera on the roof of the Exploratorium museum in San Francisco, California. The camera recorded an image every 10 seconds from before sunrise to after sunset and from mid-2009 to mid-2010. A time stamp showing the local time of day is provided on the lower right. The videos are arranged chronologically, with July 28 shown on the upper left, and January 1 located about half way down. In the videos, darkness indicates night, blue depicts clear day, while gray portrays pervasive daytime cloud cover. Many videos show complex patterns of clouds moving across the camera’s wide field as that day progresses. The initial darkness in the middle depicts the delayed dawn and fewer daylight hours of winter. Although every day lasts 24 hours, nighttime lasts longest in the northern hemisphere in December and the surrounding winter months. Therefore, finding the panel with the longest night will locate the day of winter solstice – which happens to be today in the northern hemisphere. As the videos collectively end, sunset and then darkness descend first on the winter days just above the middle, and last on the mid-summer near the bottom.

∞ Source: apod.nasa.gov/apod/ap191222.html



* This article was originally published here

Isotopes vs ancient DNA in prehistoric Scandinavia

Four of the samples from the recent Frei et al. paper on human mobility in prehistoric southern Scandinavia are in my Global25 datasheets. Their genomes were published along with Allentoft et al. back in 2015. So I thought it might be interesting to check whether their strontium isotope ratios correlated with their genomic profiles. In the Principal Component Analysis (PCA) below, RISE61 is a

* This article was originally published here

Cotton Candy' Planet Mysteries Unravel in New Hubble Observations

Illustration of Kepler 51 System
Credit: NASA, ESA, and L. Hustak, J. Olmsted, D. Player and F. Summers (STScI)

Illustration of Kepler 51 Planets Compared to Solar System
Credit: NASA, ESA, and L. Hustak, J. Olmsted, D. Player and F. Summers (STScI)




New Type of World is Unlike Anything Found in the Solar System

When astronomers look around the solar system, they find that planets can be made out of almost anything. Terrestrial planets like Earth, Mars, and Venus have dense iron cores and rocky mantles. The massive outer planets like Jupiter and Saturn are mostly gaseous and liquid. Astronomers can't peel back their cloud layers to look inside, but their composition is deduced by comparing the planet's mass (as calculated from its orbital motion) to its size. The result is that Jupiter has the density of water, and Saturn has an even lower density (it could float in a huge bathtub). These gas giants are just 1/5th the density of rocky Earth.

Now astronomers have uncovered a completely new class of planet unlike anything found in our solar system. Rather than a "terrestrial" or "gas giant" they might better be called "cotton candy" planets because their density is so low. These planets are so bloated they are nearly the size of Jupiter, but are just 1/100th of its mass. Three of them orbit the Sun-like star Kepler 51, located approximately 2,600 light-years away.

The puffed-up planets might represent a brief transitory phase in planet evolution, which would explain why we don't see anything like them in the solar system. The planets may have formed much farther from their star and migrated inward. Now their low-density hydrogen/helium atmospheres are bleeding off into space. Eventually, much smaller planets might be left behind.

"Super-Puffs" may sound like a new breakfast cereal. But it's actually the nickname for a unique and rare class of young exoplanets that have the density of cotton candy. Nothing like them exists in our solar system.

New data from NASA's Hubble Space Telescope have provided the first clues to the chemistry of two of these super-puffy planets, which are located in the Kepler 51 system. This exoplanet system, which actually boasts three super-puffs orbiting a young Sun-like star, was discovered by NASA's Kepler space telescope in 2012. However, it wasn't until 2014 when the low densities of these planets were determined, to the surprise of many.

The recent Hubble observations allowed a team of astronomers to refine the mass and size estimates for these worlds — independently confirming their "puffy" nature. Though no more than several times the mass of Earth, their hydrogen/helium atmospheres are so bloated they are nearly the size of Jupiter. In other words, these planets might look as big and bulky as Jupiter, but are roughly a hundred times lighter in terms of mass.

How and why their atmospheres balloon outwards remains unknown, but this feature makes super-puffs prime targets for atmospheric investigation. Using Hubble, the team went looking for evidence of components, notably water, in the atmospheres of the planets, called Kepler-51 b and 51 d. Hubble observed the planets when they passed in front of their star, aiming to observe the infrared color of their sunsets. Astronomers deduced the amount of light absorbed by the atmosphere in infrared light. This type of observation allows scientists to look for the telltale signs of the planets' chemical constituents, such as water.

To the amazement of the Hubble team, they found the spectra of both planets not to have any telltale chemical signatures. They attribute this result to clouds of particles high in their atmospheres. "This was completely unexpected," said Jessica Libby-Roberts of the University of Colorado, Boulder, "we had planned on observing large water absorption features, but they just weren't there. We were clouded out!" However, unlike Earth's water-clouds, the clouds on these planets may be composed of salt crystals or photochemical hazes, like those found on Saturn's largest moon, Titan.

These clouds provide the team with insight into how Kepler-51 b and 51 d stack up against other low-mass, gas-rich planets outside of our solar system. When comparing the flat spectra of the super-puffs against the spectra of other planets, the team was able to support the hypothesis that cloud/haze formation is linked to the temperature of a planet — the cooler a planet is, the cloudier it becomes.

The team also explored the possibility that these planets weren't actually super-puffs at all. The gravitational pull among the planets creates slight changes to their orbital periods, and from these timing effects planetary masses can be derived. By combining the variations in the timing of when a planet passes in front of its star (an event called a transit) with those transits observed by the Kepler space telescope, the team better constrained the planetary masses and dynamics of the system. Their results agreed with previous measured ones for Kepler-51 b. However, they found that Kepler-51 d was slightly less massive (or the planet was even more puffy) than previously thought.

In the end, the team concluded that the low densities of these planets are in part a consequence of the young age of the system, a mere 500 million years old, compared to our 4.6-billion-year-old Sun. Models suggest these planets formed outside of the star's "snow line," the region of possible orbits where icy materials can survive. The planets then migrated inward, like a string of railroad cars.

Now, with the planets much closer to the star, their low-density atmospheres should evaporate into space over the next few billion years. Using planetary evolution models, the team was able to show that Kepler-51 b, the planet closest to the star, will one day (in a billion years) look like a smaller and hotter version of Neptune, a type of planet that is fairly common throughout the Milky Way. However, it appears that Kepler-51 d, which is farther from the star, will continue to be a low-density oddball planet, though it will both shrink and lose some small amount of atmosphere. "This system offers a unique laboratory for testing theories of early planet evolution," said Zach Berta-Thompson of the University of Colorado, Boulder.

The good news is that all is not lost for determining the atmospheric composition of these two planets. NASA's upcoming James Webb Space Telescope, with its sensitivity to longer infrared wavelengths of light, may be able to peer through the cloud layers. Future observations with this telescope could provide insight as to what these cotton candy planets are actually made of. Until then, these planets remain a sweet mystery.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Source: HubbleSite



Contact:

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu

Daniel Strain
University of Colorado, Boulder, Colorado
daniel.strain@colorado.edu

Jessica Libby-Roberts / Zach Berta-Thompson
University of Colorado, Boulder, Colorado
jessica.e.roberts@colorado.edu / zachory.bertathompson@colorado.edu




Related Links:




* This article was originally published here

Commoner or elite?

I recently started looking at the correlations between Y-chromosome haplogroups and social standing in ancient Europe, and was surprised by what I learned about the five currently sampled prehistoric Scandinavians belonging to Y-haplogroup R1b. I certainly wasn't expecting to uncover these stories about a mass human sacrifice, a bog body, and an Arctic circle warrior: - The earliest Scandinavian

* This article was originally published here

Loch Kinord 9th Century Pictish Celtic Cross Slab, Loch Kinord, Dinnet, Cairngorms, 20.12.19.

Loch Kinord 9th Century Pictish Celtic Cross Slab, Loch Kinord, Dinnet, Cairngorms, 20.12.19.



* This article was originally published here

EEF-WHG-ANE test for Europeans


This test attempts to fit you to the three inferred prehistoric European populations as described in this recent preprint. The relevant Excel file can be downloaded here, and all you have to do is stick your Eurogenes K13 results into the fields provided to get the EEF-WHG-ANE ancestry proportions. A modified version for Near Eastern and Southeast European users can be accessed here.

The test is based on correlations between the average levels of the Eurogenes K13 and the ancient components among selected European populations. Below is a brief description of each of the ancient components.

Early European Farmer (EEF): apparently this is a hybrid component, the result of mixture between "Basal Eurasians" and a WHG-like population possibly from the Balkans. It's based on a 7500 year old Linearbandkeramik (LBK) sample from Stuttgart, Germany, but today peaks at just over 80% among Sardinians.

West European Hunter-Gatherer (WHG): this ancestral component is based on an 8,000 year old forager from the Loschbour rock shelter in Luxembourg, who belonged to Y-chromosome haplogroup I2a1b. However, today the WHG component peaks among Estonians and Lithuanians, in the East Baltic region, at almost 50%.

Ancient North Eurasian (ANE): this is the twist in the tale, a component based on a 24,000 year old Upper Paleolithic forager from South Central Siberia, belonging to Y-DNA R*, and known as Mal'ta boy or MA-1. This component was very likely present in Southern Scandinavia since at least the Mesolithic, but only seems to have reached Western Europe after the Neolithic. At some point it also spread into the Americas. In Europe today it peaks among Estonians at just over 18%, and, intriguingly, reaches a similar level among Scots. However, numbers weren't given in the paper for Finns, Russians and Mordovians, who, according to one of the maps, also carry very high ANE, but their results are confounded by more recent Siberian (ENA) admixture.

It's important to note that this test is only likely to be accurate for people of European ancestry, and indeed only those who aren't outliers from the main European clines of genetic diversity. For details of what that means, please consult the aforementioned paper. However, roughly speaking, if you're of European origin and don't score more than 3% East Asian, Siberian, Amerindian, South Asian, Oceanian, Northeast African and/or Sub-Saharan admixture, then you should get a coherent result. Users from the Near East and Caucasus should run the version specifically designed for them, while those from Southeastern Europe might find it useful to run both calculators and then compare the results.

Thanks to project member DESUK1 for putting this together at such short notice, and MfA for the modified version. Please post your results in the comments section below and state your ancestry when you do. This will help us to improve the accuracy of the test. My results make perfect sense, considering my Polish ancestry.

EEF 42.012706
WHG 40.52702615
ANE 17.46026785

This is my interpretation of who these components represent. Of course, this model might change when more ancient genomes are analyzed.

WHG and WHG/ANE: indigenous European hunter-gatherers
EEF: mixed European/Near Eastern Neolithic farmers
ANE/WHG: Proto-Indo-European invaders from the Eastern European steppe
ENA/ANE: early Uralics from the Volga-Ural region
EEF/WHG/ANE: late Indo-Europeans (ie. Celts, Germanics and Slavs)

Citation...

Iosif Lazaridis, Nick Patterson, Alissa Mittnik, et al., Ancient human genomes suggest three ancestral populations for present-day Europeans, bioRxiv, Posted December 23, 2013, doi: 10.1101/001552

See also...

Ancient human genomes suggest (more than) three ancestral populations for present-day Europeans

Ancient North Eurasian (ANE) levels across Asia



* This article was originally published here

Happy Winter Solstice from the Balnuaran of Clava, Inverness, 21.12.19.

Happy Winter Solstice from the Balnuaran of Clava, Inverness, 21.12.19.



* This article was originally published here

Model yourself as a mixture of ancient genomes


Update 12/05/2015: 4mix: four-way mixture modeling in R

...

This is really easy and should work well for most personal genomics customers (ie. those of European ancestry and with data files from 23andMe, FTDNA and AncestryDNA).

First of all, make sure you have your Eurogenes K15 ancestry proportions from GEDmatch. Then do the following:

- download the 4 Ancestors Oracle (here)

- download the Eurogenes ancient genomes datasheet (here)

- place everything into the same directory

- double click of the 4 Ancestors Oracle icon (the big red number 4)

- select the Eurogenes K15 ancient genomes datasheet

- type your Eurogenes K15 ancestry proportions into the fields provided

- hit the go button and let it rip

I'm not sure I'm allowed to upload the 4 Ancestors Oracle online, but I couldn't find the original link, so let's assume for the time being that I am. In any case, many thanks to Alexandr Burnashev for this great tool.

You'll also find some modern populations in the datasheet. They're there so that users with ancestry from outside of Europe don't end up with ridiculous results.

Obviously, you can edit the datasheet to explore more options by removing or adding individuals and populations. A spreadsheet of Eurogenes K15 population averages is available here. The oracle settings can also be tweaked in a couple of ways to fine tune the results.

If the calculator crashes, try replacing the periods with commas in both the datasheet and your ancestry proportions.

Please keep checking this post, because I'll attempt to update the datasheet at the link above every time a new ancient genome is published and has enough markers available to be tested with the Eurogenes K15. Eventually we might end up with a tool that covers most of the continents and many periods of history and prehistory.

I've done similar analyses of a variety of ancient genomes. For instance, StoraFörvar11, or SfF11, from Mesolithic Sweden came out 3/4 La Brana-1 and 1/4 MA-1, which translates to 3/4 Western European Hunter-Gatherer (WHG) and 1/4 Ancient North Eurasian (ANE), and lines up well with results reported recently for Swedish hunter-gatherers in scientific literature. You can see the full analysis StoraFörvar11 and a couple of other ancient genomes at the links below.

Analysis of Mesolithic Swedish forager StoraFörvar11

More ancient genomes from Sweden: Pitted Ware forager Ajvide58 and TRB farm girl Gokhem2

I'm still trying to answer a whole lot of e-mails so I won't be monitoring this post for a while. But please feel free to share your results and any tips you might have in the comments below.



* This article was originally published here

Geminid Fireball near the Lajas Aerostat

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Channel: Frankie Lucena  

The Geminid meteors are still present even though the peak was on Dec 14th. I used a Sony color CCD camera with a 12mm lens.

Video length: 0:16
Category: Science & Technology
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